Capacity control for multiple-phase ejector refrigeration systems

ABSTRACT

A multiple-phase ejector refrigeration system including a capacity control allowing part-load operation. The capacity is varied by bleeding a stream of hot gas from the discharge side of a vapor compressor and introducing it in a controlled manner into the liquid nozzle of the multiple-phase ejector. This has the effect of first increasing and then reducing the efficiency of the nozzle as the bleed rate increases, thereby affecting the efficiency and flow capacity of the ejector unit.

United States Patent Newton June 20, 1972 54 CAPACITY CONTROL FORMULTIPLE. 3,276,216 10/1966 Papapanu ..62/soo 3,496,735 2/1970l-laisma.... ..62/500 PHASE EJECTOR REFRIGERATION SYSTEMS PrimaryExaminer-Meyer Perlin Attomey-Donald W. Banner, William S. McCurry andJohn Inventor: Alwin B. Newton, York, Pa.

W. Butcher Assignee: Borg-Warner Corporation, Chicago, Ill.

Filed: Feb. 8, 1971 ABSTRACT Appl' l 13224 A multiple-phase ejectorrefrigeration system including a capacity control allowing part-loadoperation. The capacity is us. Cl ..62/l16, 62/191, 62/500 varied bybleeding a stream gas dischalge Side of a vapor compressor andintroducing it in a controlled Int. Cl ..F25b 1/00 manner into theliquid nozzle of the multiple-phase e ector. Field of Search 116, 1 hasLhe efiect offirst increasing and then reducing the ficiency of thenozzle as the bleed rate increases, thereby af- Refelences Ciied fectingthe efficiency and flow capacity of the ejector unit.

UNITED STATES PATENTS 28 Claims, 5 Drawing Figures 2,852,922 9/1958Neumann ..62/500 4o 24 44 45 19 25 a0 28 30 .9 20 A 48 LOAD PNENTEBJUHZOI972 3,570,519

sv WZM ATTORNEY PHTEMTEMmo 1972 3579.519 sum 2 or 2 I T f) LOAD \J 5 5INVENTOR AAW/A A/VEWTO/V ATTORNEY CAPACITY CONTROL FOR MULTIPLE-PHASEEJECTOR REFRIGERATION SYSTEMS BACKGROUND AND SUMMARY OF THE INVENTIONThis invention relates to improved refrigeration systems and moreparticularly to a capacity control for refrigeration systems utilizing amultiple-phase ejector apparatus as one of the primary components insaid refrigeration system.

U. S. Pat. No. 3,277,660 issued to Clarence A. Kemper et al. on Oct. ll,1966, describes several novel refrigeration systems in whichmultiple-phase ejectors are employed in place of, or in combinationwith, a vapor compressor used in the conventional vapor cyclerefrigeration system. In each of the systems described in the Kemper etal. patent, a stream of high pressure liquid refrigerant is introducedinto the inlet side of a nozzle which is adapted to accelerate theliquid refrigerant stream to form a supersonic velocity, two-phase,vapor-liquid refrigerant stream. This two-phase stream is then mixedwith a low-pressure vapor refrigerant stream to provide a singlerefrigerant stream. Next, the velocity of the single refrigerant streamis decreased by expansion through a nonle until the temperature and thepressure are greater than the temperature and pressure of the vaporstream before it is increased in velocity.

One of the advantages of the refrigeration system described in theKemper et al. patent, particularly the work input system illustrated inFIG. 3, is that it is extremely flexible and can be easily designed tomeet specific requirements, such as condensing and evaporatingtemperatures, compressor capacity, etc. One of the reasons for thisflexibility is that the system, contrary to the conventionalrefrigeration system, works at three different pressures: The high sidepressure on the discharge side of the vapor compressor; and intermediatepressure, as measured on the suction side of the vapor compressor; and alow evaporating pressure, as measured in the evaporator or at the inletside of the ejector. In effect, the ejector has the capability ofsignificantly boosting the pressure on the suction side of the vaporcompressor. This reduces the pressure difference against which thecompressor has to work, so that a smaller compressor can be used toproduce a given capacity, or alternatively, the same size compressor canbe used with increased capacity.

The present invention may be considered generally as a refrigerationsystem which utilizes to the best advantage the unique features of theKemper et al. multiple-phase ejector. The Kemper et al. system does notdisclose any mechanism by which the capacity may be convenientlycontrolled. The present invention proposes to utilize a stream of hotgas from the discharge side of a vapor compressor to be introduced incontrolled quantities into the high pressure liquid nozzle to change thecharacter and efficiency of the flow of said liquid during itsacceleration to a supersonic velocity, two-phase, vapor-liquid stream.

Accordingly, a principal object of the invention is to provide animproved capacity control for a multiple-phase ejector refrigerationsystem.

Another object of the invention is to provide an improved capacitycontrol for a multiple-phase ejector refrigeration system in which thecapacity and effectiveness of the liquid nozzle of the ejector is variedby feeding hot gas from a compressor to the nozzle.

Additional objects and advantages will be apparent from the followingdetailed description taken in conjunction with the drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic or diagrammatic viewof a refrigeration system embodying my improved control including athermostatically-operated valve;

FIG. 2 is a detailed cross-sectional view of the valve;

FIG. 3 is a schematic or diagrammatic view of a modification of therefrigeration system shown in FIGS. 1 and 2;

FIG. 4 is a modification of portions of the refrigeration systems shownin FIGS. 1 and 3; and

FIG. 5 is another modification of portions of the refrigeration systemshown in FIGS. 1 and 3.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, therefrigeration system of the present invention includes a vaporcompressor VC, a condenser C, an evaporator E, a multiple-phase ejectorM and a vapor-liquid separator S. Refrigerant vapor of any suitabletype, such as R-12 for example, is supplied to the suction side ofcompressor VC through conduit 10, compressed, and forwarded throughconduit 12 to the condenser C. Heat is removed from the hot refrigerantvapor by the condenser heat exchanger 14 through which a coolant iscirculated (usually water, but, in some cases, air). The hot vapor iscaused to liquefy in the condenser and is delivered through conduit 16to the multiple-phase ejector M which has means defining a liquidchamber 19, in the form of a tube, having an inlet 20 for theintroduction of the high-pressure liquid stream, said liquid chamber 19communicating with a first nozzle 22 provided at one end of the tube,discharging into a mixing chamber 24 having its flow axis substantiallyaligned with the longitudinal axis of the nozzle 22. The nozzle 22 iscontoured by respective converging-diverging internal flow paths 25 and26 in which the minimum cross-sectional area at 28 is sufficientlysmall, relative to the outlet area and other dimensions at 30, as toenable the production of a high-velocity, two-phase, liquidvapor stream,which may be supersonic. A second input inlet 32 is provided for theintroduction of a low-pressure vapor stream communicating through meansdefining a vapor chamber 33 with a second nozzle 36 locatedsubstantially concentric with the first nozzle 22 for introducing at 40a highvelocity vapor refrigerant stream into the inlet opening of themixing chamber 24 so as to be placed in intimate contact with thetwo-phase stream resulting at 30 from the first nozzle 22, thereby tocombine the streams. The resulting mixed stream continues through themixing section, and a section 42 of substantially constant flow area,into a diverging chamber 44, the function of the latter being todecrease the velocity of the combined streams at 46 to a velocity atwhich the temperature and the pressure of the combined stream is greaterthan the temperature and the pressure of the vapor refrigerant streamprior to passage through the second nozzle 36. The divergent chamber 44has an outlet at 45 from which the ejector-exit stream is withdrawn anddelivered into the vapor-liquid separator S. The latter comprises meansdefining a chamber 48 surrounding and in communication with the outletportion of the ejector nozzle. Liquid refrigerant collects in the lowerportion of chamber 48 and is supplied to the evaporator E throughconduits 50 and 52. For a more detailed disclosure and explanation ofthe above described refrigeration system including particularly themultiple-phase ejector M and its operation, reference is made to U. S.Pat. No. 3,277,660.

Conduits 50 and 52 are connected by means 54 for maintaining thepressure differential achieved at various loads between the diffuseroutlet 45 and conduit 34. The pressure at 45 is essentially the samepressure existing at the suction side of the vapor compressor VC, whilethe pressure at 34 is essentially the pressure within the evaporator E.Means 54 may take the form of a float valve or orifice, but ispreferably a liquid dropleg designed to accommodate a suitable pressuredifferential, say 5-10 p.s.i. at full load for refrigerants such asR-22. The main function of liquid dropleg 54 is to provide an interfacebetween liquid returning to the evaporator through conduit 52, and vaporresiding in chamber 48 and entering the evaporator B through conduit 50.No vapor should enter conduit 52 and no liquid should enter conduit 10.The pressure loss in this action should not exceed the pressure risebetween conduit 34 and chamber 48. Liquid, fed to the evaporator E,evaporates and the vapor is forwarded to the second nozzle 36 in themultiple-phase ejector M through conduit 34. In vaporizing, therefrigerant absorbs heat so that, in the conventional system, a secondcooling coil is provided in the evaporator, such as in a conventionalliquid chiller wherein water is circulated through a closed circuitincluding a tube bundle 56 (in the evaporator) and the load.

As pointed out in the preliminary remarks, the principal feature of theinvention comprises a capacity control which affects the efficiency ofthe multiple-phase ejector unit M. In a preferred embodiment, ejectorefiiciency is controlled by bleeding off a portion of the vapor from hotvapor conduit 12 through conduit 60 to the inlet nozzle 22 receiving theliquid from the condenser. The vapor, as it mixes with the liquidstream, disrupts the flow through the nozzle so that the efficiency ofthe nozzle flow may be conveniently and accurately controlled.

Control of the flow of hot gas is preferably in response to the absolutesuperheat of the gas being delivered to the inlet side of vaporcompressor VC. Accordingly, a pressure tap 62 and a thermal-sensing bulb64 are respectively responsive to the pressure and temperature of thegas in the suction conduit and which are operable to control a valve 66in the bleed conduit between the hot gas conduit and the inlet nonle 22.More particularly and referring to FIG. 2, valve 66 comprises a hollowcasing 67 provided with a flexible diaphragm 68 dividing the easing intoan upper compartment 69 and a lower compartment 70 and supporting avertically-movable valve member 71 having its lower cone-shaped end 72disposed adjacent a circular opening 73 of the valve seat locatedbetween and connecting conduits 60 and 61 so that movement of the valvemember will control the quantity of gas flowing from conduit 12 to theconduit 67 and the inlet nozzle 22. The compartment 69 is connected tothe refrigerant filled, pressureresponsive thermal-sensing bulb 64 by aconduit 74 so that movement of the diaphragm 68 will occur uponexpansion and contraction of the vapor in compartment 69 in response tovariations in temperature of the refrigerant in the bulb sensing thetemperature of the gas in conduit 10. The vapor compartment 70 is sealedfrom communication with the gas flowing in conduits 60 and 67 by a seal75 connected to the casing 67 and in sealing engagement with valvemember 71, which is biased open by spring 79. As vapor compartment 70 isconnected by conduit 62 to the conduit 10, any variations in thepressure of the gas in conduit 10 will cause the diaphragm to be movedin response thereto.

The operation of the control mechanism may be described as follows: (1)a rise in the absolute superheat of gas entering the vapor compressorwould indicate an increase in the load requiring additional capacity.The joint action of the pressure tap and the bulb would thus tend toclose valve 66 to throttle any flow of gas into the nozzle and therebyincrease the efficiency of the same; (2) a drop in the absolutesuperheat would indicate that a reduction in capacity is required; thebulb and the pressure tap would cooperate to open the valve to bleedadditional gas into the nozzle, thus reducing the efficiency of thefluid flow into the multiple-phase ejector M and producing acorresponding reduction in capacity for the entire system.

Accordingly, the control of the present invention causes the capacity ofthe refrigeration system to be varied by bleeding a stream of hot gasfrom the discharge side of the vapor compressor and introducing it in acontrolled manner into the liquid nozzle of the ejector. Introduction ofa small amount of vapor into the nozzle inlet stream improves theefficiency of the nozzle but normally reduces the total flow ratethrough the nozzle. Introduction of an increased amount of vapor intothe nozzle inlet stream may reduce the efficiency of the noule, but moreimportantly always reduces the total mass flow rate. The introduction ofthe high pressure gas bleed controls the amount of refrigerant passingthrough the nozzle and causes the nozzle to meter the flow, similarly tothe operation of a thermostatic expansion valve in a conventionalrefrigeration system.

A secondary efi'ect occurs by the action of the vapor flow into theinlet region of the nozzle. More particularly the hot uncondensed gashas a higher enthalpy than the liquid which could enter through conduit16. Accordingly, when the temperature of the vapor in conduit 10, sensedby bulb 64,

reduces with no change in pressure of the vapor in conduit 62, there isprovided an indication of reduction in superheat and a need to reducethe total supply of refrigerant to the evaporator circuit. In thisinvention, reduction of the total supply of refrigerant to theevaporator conduit occurs by valve 66 opening more widely, allowing ahigher flow rate of vapor and consequent reduction in the total massflow through the nonle 22. Thus, liquid entering through conduit 16 isreduced similarly to the operation of a conventional expansion valvelocated in conduit 16 if the valve was somewhat closed in response tothe reduction in superheat. Another effect of the entrance of hot gas isthe equivalent of the hot gas bypass in conventional systems, but withthe added advantage that the hot gas assists in compressing the vaporfrom evaporator 34 and thus both the vapor and hot gas flow itselfenters the compressor at a higher pressure than would otherwise be thecase.

The embodiment of the invention illustrated in FIG. 3 is an improvementof the refrigeration system of FIG. 1 and 2, like parts being similarlyidentified numerically or alphabetically in the several views. As inFIGS. 1 and 2, FIG. 3 also discloses a refrigeration system having amultiple-phase ejector M, a vapor compressor VC, a condenser C, anevaporator E, and

vapor-liquid separator S, connected together and arranged in arefrigerant flow pattern. In addition, as in FIG. I, valve 66 connectsthe hot vapor conduit 60 to the liquid chamber 19 and senses thepressure and temperature of the vapor in the suction conduit 10 to thecompressor to open the valve 66 and thereby reduce capacity requirementsof the refrigeration system when the superheated vapor drops below anormal level. One improvement disclosed in FIG. 3 is the provision of avalve 76 between and connecting conduit 60 and valve 66 and closable tooverride valve 66 by discontinuing vapor flow to the inlet nozzle 22when valve 66 is open. Valve 76 may be connected, as shown by dottedlines, to a controlling timer on a float (not shown) in compressorcrankcase 9 to cause liquid flood-back and, therefore, oil return atperiodic intervals. Another improvement is valve 77 in conduit 78between and directly connecting conduit 60 and conduit 61 and, thereby,bypassing valves 66 and 76. Accordingly, valve 77 can override theeffect of valve 66 and 76 by feeding vapor to the inlet nozzle 22 toreduce capacity even though valves 66 and 76 are closed. Valve 77 can beconnected to a safety control such as a high or low pressure sensor, orlow water temperature sensor. It will be apparent that valves 66, 76 and77 control the flow of hot refrigerant vapor or gas from the compressorVC to the liquid chamber 19 and thereby to the inlet nozzle 22 of theejector M. By thus introducing the gas into the nozzle 22, these valvesreduce the capacity of the ejector M and thereby of the refrigerationsystem.

As shown in FIGS. 4 and 5, conduit 61 may be alternately connected tothe diffuser section (FIG. 4), or to the eductor section (FIG. 5) of theejector and similar results achieved with varying flow levels in conduit61.

While this invention has been described in connection with specificembodiments thereof, it is to be understood that this is by way ofillustration and not by way of limitation; and the scope of the appendedclaims should be construed as broadly as the prior art will permit.

What is claimed is:

l. A refrigeration system comprising an evaporator; a vapor compressoradapted to compress a refrigerant; a condenser receiving hot refrigerantvapor from said compressor, said condenser operating to liquefy saidrefrigerant; a multiplephase ejector comprising means defining a liquidchamber having a liquid inlet, means defining a vapor chamber having avapor inlet, and an outlet discharging a two-phase vapor-liquidrefrigerant stream; means for supplying high pressure liquid from thecondenser to said liquid inlet; a vapor-liquid separator receiving thetwo-phase refrigerant stream and adapted to separate said phases; meansfor transferring the liquid phase from said separator to saidevaporator; means for connecting said evaporator to said vapor inlet;means connecting said separator to said compressor to deliverrefi'igerant vapor to the suction side of said compressor; and means forsupplying a portion of the hot vapor, flowing from said compressor tosaid condenser, to one of said ejector chambers.

2. A system as defined in claim 1 in which said hot vaporsupplying meanssupplies said hot vapor portion to said ejector liquid chamber.

3. A system as defined in claim 2 in which said hot vaporsupplying meansis operative to supply said hot vapor portion to said ejector liquidchamber at a controlled rate in response to the capacity requirements ofsaid system.

4. A system as defined in claim 2 in which said hot vaporsupplying meansincludes a conduit conducting said hot vapor portion to said liquidchamber, means controlling vapor flow in said conduit and including avalve, and means for operating said valve.

5. A system as defined in claim 4 in which said valve-operating meansincludes means for sensing the absolute superheat of vapor delivered tothe suction side of said vapor compressor.

6. A system as defined in claim 4 in which said valve operating meansincludes means responsive to variations in pressure of the vapordelivered to the suction side of said compressor.

7. A system as defined in claim 4 in which said valve-operating meansincludes means responsive to variations in pressure and temperature ofthe vapor delivered to the suction side of said compressor.

8. A system as defined in claim 4 in which said valve includes a movablevalve member operative to control the flow of vapor through saidconduit; and said valve-operating means includes a casing, a flexiblediaphragm in said casing and defining a compartment, said diaphragmbeing connected to said valve member, a thermal-sensing memberresponsive to variations in the temperature of the refrigerant vapordelivered to the suction side of said compressor and connected to saidcompartment to effect movement of said diaphragm and thereby move saidvalve member.

9. A system as defined in claim 4 in which said valve includes a movablevalve member operative to control the flow of vapor through saidconduit; and said valve-operating means includes a casing, a flexiblediaphragm in said casing and defining a vapor compartment, saiddiaphragm being connected to said valve member, passage means connectedto said separator-and compressor-connecting means and to said vaporcompartment for providing refrigerant vapor to said vapor compartment toeffect movement of said diaphragm, in response to variations in thepressure of the refrigerant vapor, to move said valve member.

10. A system as defined in claim 4 in which said valve includes amovable valve member operative to control the flow of vapor through saidconduit; and said valve-operating means includes a casing having aflexible diaphragm in said casing and dividing said casing to providespaced first and second compartments, said diaphragm being connected tosaid valve member, a thermal-sensing bulb responsive to variations inthe temperature of the refrigerant vapor delivered to the suction sideof said compressor and connected to said first compartment to effectmovement of said diaphragm and thereby move said valve member, saidvalve-operating means further including passage means connecting saidsecond compartment and said separator-and compressor-connecting meansfor providing refrigerant vapor to said vapor compartment to effectmovement of said diaphragm, in response to variations of the pressure ofthe refrigerant vapor, to move said valve member in cooperation withmovement of said valve member by the variations in pressure in saidfirst compartment controlled by said bulb.

11. A system as defined in claim 3 in which said hot vaporsupplyingmeans includes a first conduit conducting said hot vapor portion to saidliquid chamber; a first valve in said first conduit; means for operatingsaid first valve to supply said hot vapor portion to said liquid chamberat a controlled rate in response to the capacity requirement of saidsystem, and a second conduit in parallel with said first conduit andbypassing said first valve to conduct said hot vapor portion to saidliquid chamber, and a second valve in said second conduit.

12. A system as defined in claim 11 in which said first valveoperatingmeans includes means for sensingthe absolute superheat of vapordelivered to the suction side of said vapor compressor.

13. A system as defined in claim 1 1 in which said first valveoperatingmeans includes means for sensing variations in the pressure of the vapordelivered to the suction side of said vapor compressor.

14. A system as defined in claim 11 in which said first valveoperatingmeans includes means for sensing variations in pres sure and temperatureof the vapor delivered to the suction side of said vapor compressor.

15. A system as defined in claim 3 in which said hot vaporsupplyingmeans includes a conduit conducting said hot vapor portion to saidliquid chamber; a first valve in said conduit; means for operating saidfirst valve to supply said hot vapor portion to said liquid chamber at acontrolled rate in response to the capacity requirements of said system,and a second valve in series with said first valve in said conduit.

16. A system as defined in claim 3 in which said hot vaporsupplyingmeans includes a conduit conducting said hot vapor portion to saidliquid chamber; a first valve in said conduit; means for operating saidfirst valve to supply said hot vapor portion to said liquid chamber at acontrolled rate in response to the capacity requirements of said system,and a second valve in series with said first valve in said conduit andcontrolling the supply of said hot vapor portion to said first valve.

17. A system as defined in claim 15 in which said first valveoperatingmeans includes means for sensing the absolute superheat of vapordelivered to the suction side of said vapor compressor.

18. A system as defined in claim 15 in which said first valveoperatingmeans includes means for sensing variations in the pressure of the vapordelivered to the suction side of said vapor compressor.

19. A system as defined in claim 15 in which said first valveoperatingmeans includes means for sensing variations in pressure and temperatureof the vapor delivered to the suction side of said vapor compressor.

20. A system as defined in claim 3 in which said hot vaporsupplyingmeans includes a first conduit conducting said hot vapor portion to saidliquid chamber; a first valve in said first conduit; means for operatingsaid first valve to supply said hot vapor portion to said liquid chamberat a controlled rate in response to the capacity requirements of saidsystem, and a second valve disposed in said first conduit and in serieswith said first valve, a second conduit disposed in parallel with saidfirst conduit and bypassing said first valve and said second valve toconduct said hot vapor portion to said liquid chamber, and a third valvein said second conduit.

21. A system as defined in claim 20 in which said first valveoperatingmeans includes means for sensing the absolute superheat of vapordelivered to the suction side of said vapor compressor.

22. A system as defined in claim 20 in which said first valveoperatingmeans includes means for sensing variations in the pressure of the vapordelivered to the suction side of said vapor compressor.

23. A system as defined in claim 20 in which said first valveoperatingmeans includes means for sensing variations in pressure and temperatureof the vapor delivered to the suction side of said vapor compressor.

24. A system as defined in claim 1 in which said vapor chamber of saidejector comprises an educator section and a diffuser section, and saidhot vapor supply means is connected to, and provides said hot vaporportion to, one of said eductor and diffuser sections.

25. A system as defined in claim 24 in which said hot vapor supply meansprovides said hot vapor portion to said eductor section. v

sion of said vapor in response to the capacity requirements of 10 saidsystem, such that increased vapor is supplied during reduced capacitydemand.

28. In a vapor cycle refrigerant system including a compressor, acondenser and an evaporator connected to provide a closed refrigerationcircuit; a multiple-phase ejector connected in said circuit to boost thesuction pressure of vapor supplied to said compressor, said ejectorbeing driven by highpressure liquid refrigerant; means for separatingthe twophase stream leaving said ejector and returning the vapor phaseto said compressor and delivering a liquid phase to said evaporator, theimprovement comprising means for disrupting the efficiency of thepressure boosting capacity of said ejector by admitting vapor to thesubstantially liquid driving stream from said condenser.

4 t I I i UNITED STATES PATENT @FFIQE I QERTHEQAEE @F QQRREQHQN PatentNo. 3,67%519 Dated June 20, 1972 Inventor(s) Alwin Bo Newton It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 6, line 69, educator should read eductor Signed and sealed this19th day of December 19720 (SEAL) Attest:

EDWARD B LFLE'iCI-IER ,JRe ROBERT GOTTSCHALK Attescing OfficerCommissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 w u.s.sovznumzm' PRINTING OFFICE: 1959 0-366-334.

1. A refrigeration system comprising an evaporator; a vapor compressoradapted to compress a refrigerant; a condenser receiving hot refrigerantvapor from said compressor, said condenser operating to liquefy saidrefrigerant; a multiple-phase ejector comprising means defining a liquidchamber having a liquid inlet, means defining a vapor chamber having avapor inlet, and an outlet discharging a two-phase vapor-liquidrefrigerant stream; means for supplying high pressure liquid from thecondenser to said liquid inlet; a vapor-liquid separator receiving thetwo-phase refrigerant stream and adapted to separate said phases; meansfor transferring the liquid phase from said separator to saidevaporator; means for connecting said evaporator to said vapor inlet;means connecting said separator to said compressor to deliverrefrigerant vapor to the suction side of said compressor; and means forsupplying a portion of the hot vapor, flowing from said compressor tosaid condenser, to one of said ejector chambers.
 2. A system as definedin claim 1 in which said hot vapor-supplying means supplies said hotvapor portion to said ejector liquid chamber.
 3. A system as defined inclaim 2 in which said hot vapor-supplying means is operative to supplysaid hot vapor portion to said ejector liquid chamber at a controlledrate in response to the capacity requirements of said system.
 4. Asystem as defined in claim 2 in which said hot vapor-supplying meansincludes a conduit conducting said hot vapor portion to said liquidchamber, means controlling vapor flow in said conduit and including avalve, and means for operating said valve.
 5. A system as defined inclaim 4 in which said valve-operating means includes means for sensingthe absolute superheat of vapor delivered to the suction side of saidvapor compressor.
 6. A system as defined in claim 4 in which saidvalve-operating means includes means responsive to variations inpressure of the vapor delivered to the suction side of said compressor.7. A system as defined in claim 4 in which said valve-operating meansincludes means responsive to variations in pressure and temperature ofthe vapor delivered to the suction side of said compressor.
 8. A systemas defined in claim 4 in which said valve includes a movable valvemember operative to control the flow of vapor through said conduit; andsaid valve-operating means includes a casing, a flexible diaphragm insaid casing and defining a compartment, said diaphragm being connectedto said valve member, a thermal-sensing member responsive to variationsin the temperature of the refrigerant vapor delivered to the suctionside of said compressor and connected to said compartment to effectmovement of said diaphragm and thereby move said valve member.
 9. Asystem as defined in claim 4 in which said vaLve includes a movablevalve member operative to control the flow of vapor through saidconduit; and said valve-operating means includes a casing, a flexiblediaphragm in said casing and defining a vapor compartment, saiddiaphragm being connected to said valve member, passage means connectedto said separator-and compressor-connecting means and to said vaporcompartment for providing refrigerant vapor to said vapor compartment toeffect movement of said diaphragm, in response to variations in thepressure of the refrigerant vapor, to move said valve member.
 10. Asystem as defined in claim 4 in which said valve includes a movablevalve member operative to control the flow of vapor through saidconduit; and said valve-operating means includes a casing having aflexible diaphragm in said casing and dividing said casing to providespaced first and second compartments, said diaphragm being connected tosaid valve member, a thermal-sensing bulb responsive to variations inthe temperature of the refrigerant vapor delivered to the suction sideof said compressor and connected to said first compartment to effectmovement of said diaphragm and thereby move said valve member, saidvalve-operating means further including passage means connecting saidsecond compartment and said separator-and compressor-connecting meansfor providing refrigerant vapor to said vapor compartment to effectmovement of said diaphragm, in response to variations of the pressure ofthe refrigerant vapor, to move said valve member in cooperation withmovement of said valve member by the variations in pressure in saidfirst compartment controlled by said bulb.
 11. A system as defined inclaim 3 in which said hot vapor-supplying means includes a first conduitconducting said hot vapor portion to said liquid chamber; a first valvein said first conduit; means for operating said first valve to supplysaid hot vapor portion to said liquid chamber at a controlled rate inresponse to the capacity requirement of said system, and a secondconduit in parallel with said first conduit and bypassing said firstvalve to conduct said hot vapor portion to said liquid chamber, and asecond valve in said second conduit.
 12. A system as defined in claim 11in which said first valve-operating means includes means for sensing theabsolute superheat of vapor delivered to the suction side of said vaporcompressor.
 13. A system as defined in claim 11 in which said firstvalve-operating means includes means for sensing variations in thepressure of the vapor delivered to the suction side of said vaporcompressor.
 14. A system as defined in claim 11 in which said firstvalve-operating means includes means for sensing variations in pressureand temperature of the vapor delivered to the suction side of said vaporcompressor.
 15. A system as defined in claim 3 in which said hotvapor-supplying means includes a conduit conducting said hot vaporportion to said liquid chamber; a first valve in said conduit; means foroperating said first valve to supply said hot vapor portion to saidliquid chamber at a controlled rate in response to the capacityrequirements of said system, and a second valve in series with saidfirst valve in said conduit.
 16. A system as defined in claim 3 in whichsaid hot vapor-supplying means includes a conduit conducting said hotvapor portion to said liquid chamber; a first valve in said conduit;means for operating said first valve to supply said hot vapor portion tosaid liquid chamber at a controlled rate in response to the capacityrequirements of said system, and a second valve in series with saidfirst valve in said conduit and controlling the supply of said hot vaporportion to said first valve.
 17. A system as defined in claim 15 inwhich said first valve-operating means includes means for sensing theabsolute superheat of vapor delivered to the suction side of said vaporcompressor.
 18. A system as defined in claim 15 in which said firstvalve-operating means includes means for seNsing variations in thepressure of the vapor delivered to the suction side of said vaporcompressor.
 19. A system as defined in claim 15 in which said firstvalve-operating means includes means for sensing variations in pressureand temperature of the vapor delivered to the suction side of said vaporcompressor.
 20. A system as defined in claim 3 in which said hotvapor-supplying means includes a first conduit conducting said hot vaporportion to said liquid chamber; a first valve in said first conduit;means for operating said first valve to supply said hot vapor portion tosaid liquid chamber at a controlled rate in response to the capacityrequirements of said system, and a second valve disposed in said firstconduit and in series with said first valve, a second conduit disposedin parallel with said first conduit and bypassing said first valve andsaid second valve to conduct said hot vapor portion to said liquidchamber, and a third valve in said second conduit.
 21. A system asdefined in claim 20 in which said first valve-operating means includesmeans for sensing the absolute superheat of vapor delivered to thesuction side of said vapor compressor.
 22. A system as defined in claim20 in which said first valve-operating means includes means for sensingvariations in the pressure of the vapor delivered to the suction side ofsaid vapor compressor.
 23. A system as defined in claim 20 in which saidfirst valve-operating means includes means for sensing variations inpressure and temperature of the vapor delivered to the suction side ofsaid vapor compressor.
 24. A system as defined in claim 1 in which saidvapor chamber of said ejector comprises an eductor section and adiffuser section, and said hot vapor supply means is connected to, andprovides said hot vapor portion to, one of said eductor and diffusersections.
 25. A system as defined in claim 24 in which said hot vaporsupply means provides said hot vapor portion to said eductor section.26. A system as defined in claim 24 in which said hot vapor supply meansprovides said hot vapor portion to said diffuser section.
 27. A methodof controlling the capacity of a multiple-phase ejector comprising thesteps of delivering high-pressure liquid into said multiple-phaseejector to produce a supersonic, mixed-phase refrigerant stream;introducing vapor into the inlet side of a nozzle during acceleration ofsaid stream to reduce the efficiency of said nozzle; and controlling theadmission of said vapor in response to the capacity requirements of saidsystem, such that increased vapor is supplied during reduced capacitydemand.
 28. In a vapor cycle refrigerant system including a compressor,a condenser and an evaporator connected to provide a closedrefrigeration circuit; a multiple-phase ejector connected in saidcircuit to boost the suction pressure of vapor supplied to saidcompressor, said ejector being driven by high-pressure liquidrefrigerant; means for separating the two-phase stream leaving saidejector and returning the vapor phase to said compressor and deliveringa liquid phase to said evaporator, the improvement comprising means fordisrupting the efficiency of the pressure boosting capacity of saidejector by admitting vapor to the substantially liquid driving streamfrom said condenser.